Abstract: In order to know the bio-availability of potassium in livestock and poultry manure, four kinds of livestock and poultry manure including cattle manure, pig manure, duck manure and chicken manure were collected from large-scale farms in Hangzhou. The chemical forms of potassium were analyzed and the soil cultivation experiments were conducted. The results showed that the total K content in the manure ranged from 4.87 to 53.40 g/kg, and the average value was 21.50 g/kg. Potassium content in livestock and poultry manure decreased in the order of pig manure, chicken manure, duck manure and cattle manure. Bio-availability of K in livestock and poultry manure was very high. The average proportion of available K in the total K was 49.4%, and the average proportion of slow-release K in the total K was 32.4%. Most potassium in the manure could be released into soil and became available K in a short time after the manure was applied to soil.